While these ARE low-end optics, they're perfectly good enough for range use.  The problem is that you still need a good mount, and a good mount is going to run you more (quite a bit more) than the ProPoint.

If you have a carry handle upper, you want the ARMS #39 rail, and if you have a flattop, you'll need an ARMS #38EXT rail (recommended) or GG&G Fire Rail (not recommended, since the #38 comes with a #40-type BUIS already).

With most cheaper rails, you either won't be able to mount the optic far enough forward, or in the case of most of the carry handle mounts, it will constantly shoot loose.

-Troy